<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title></title>
    <meta charset="utf-8" />
    <style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
 
        html, body {
            height: 100%;
        }
 
        .wrap {
            display: flex;
            flex-direction: column;
            height: 100%;
        }
 
        header {
            height: 50px;
            line-height: 50px;
            text-align: center;
            background-color: #ccc;
            border-bottom: 1px solid #999;
        }
 
        footer {
            height: 50px;
            line-height: 50px;
            text-align: center;
            background-color: #ccc;
            border-top: 1px solid #999;
        }
 
        .main {
            flex: 1;
            position: relative;
        }
 
        .panel {
            position: absolute;
            width: 100%;
            height: 100%;
            background-color: #ccc;
        }
    </style>
</head>
<body>
    <div class="wrap">
        <header>
            头部
        </header>
        <div class="main">
            <div class="panel">
                <pre>
                    父容器position:relative;
                    子元素position:absolute;
                    width: 100%;
                    height:100%;

                    父容器display:flex后，子元素的内部元素height:100%无效解决方法
                </pre>
            </div>
        </div>
        <footer>
            底部
        </footer>
    </div>
</body>
</html>
